"It's been a lifelong dream to be an NFL head coach and however that opportunity presents itself is fine with me," Pettine said.

The Browns first interviewed Pettine last Thursday, then met with him again on Tuesday in Mobile, Ala., where Pettine had been attending Senior Bowl practices for the Bills.

"We are thrilled to announce Mike Pettine as the new head coach of the Cleveland Browns," Haslam said. "Mike is the epitome of what we want the Browns to be -- tough, aggressive and innovative -- with a blue-collar, team-first mentality. He knows what's necessary to beat teams in the AFC North. Most importantly, Mike has repeatedly shown the ability to lead his players to consistent improvement and success, clearly what we are striving for as he leads the Cleveland Browns moving forward."

"We wanted to be thorough from the start, and we interviewed as many people as we could," Banner said. "From that group, we hired the best individual for this job. Our players and fans are going to really enjoy Mike Pettine and his leadership style. We're excited to have him out in front of our team, and we look forward to working closely with him."

The son of a high school coaching legend in Pennsylvania, Pettine is a disciple of New York Jets coach Rex Ryan. Pettine was the linebackers coach when Ryan was defensive coordinator in Baltimore, then joined Ryan with the Jets as the team's defensive coordinator.

When Pettine's contract expired after the 2012 season, he joined the Bills as defensive coordinator. The Jets ranked first in defense in 2009, and this season the Bills ranked second in the league with 57 sacks.

Pettine enters a difficult situation, as he becomes the Browns' third coach in as many years. He also takes over after Rob Chudzinski was given one season, but the subject of job security was not one that scared away Pettine.

"I'll always bet on myself," he said. "I don't want to to back away from a job because of a perceived lack of security."

The Browns have not won more than five games in any of the previous six seasons, and fan unrest and impatience with the team has been strong. While fans and media picked at the Browns for the amount of time it took to hire a coach -- Chudzinski was fired the night the season ended -- Pettine badly wanted the job, according to people in Buffalo.

In late December, a panel of former coaches and general managers had Pettine on a list of worthy candidates for future openings. The Bills did not want to lose him.

Whoever the Bills hire as the next defensive coordinator will be the team's fourth in four seasons, a fact not lost on safety Aaron Williams, who tweeted about the high turnover rate Thursday.

This is a crazy business. It'll be my fourth year in the NFL and I've had a new DC every year

Pettine believes in an aggressive, attacking defense like Ryan does, and this season the Bills allowed the league's lowest completion percentage (55.3 percent) after the Jets had held quarterbacks to 52.6 percent the previous four years.

Buffalo blitzed nearly 40 percent of the time when the opposing quarterback dropped back to pass. Buffalo's run defense, though, struggled, finishing 28th in the league. Even the Browns' woeful rushing offense managed to run on the Bills.

Pettine is direct, forceful and will attack the same way former Browns defensive coordinator Ray Horton did -- with multiple fronts and different personnel groups.

The Browns submitted a request to Buffalo to interview Bills LB coach Jim O'Neil to become Cleveland's defensive coordinator, league sources said. O'Neil and Pettine also worked together with the Jets.

Information from ESPN NFL Insider Adam Schefter was used in this report.

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